1993/12/01 by T. J. Turner, K. Nandra, I. M. George +2 · 59 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxy #Gamma-ray bursts and supernovae #Line-of-sight #Physics #RADIUS #ROSAT #Spectral line #Stellar, planetary, and galactic studies
paper · doi:10.1086/173466
published in The Astrophysical Journal 419, 127 (IOP Publishing)
openalex publication_date 1993/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
We present a high signal-to-noise ROSAT position sensitive proportional counter (PSPC) observation of the Seyfert 1 galaxy NGC 3783. The 0.1-2.5 keV spectrum shows strong evidence for an absorption edge most likely associated with O VII-VIII. Such a feature, which has now been detected in a number of PSPC spectra (Nandra et al.; Nandra & Pounds; Turner et al.), is the signature of highly ionized material, the so-called warm absorber, in the line of sight to the X-ray source. The result is strongly supported by analysis of previously unpublished Ginga data and reanalysis of a 1985 EXOSAT observation of NGC 3783. We show that the warm absorber is plausibly located at a radius ≲10<SUP>18</SUP> cm from the X-ray source, possibly in an outflowing wind.